Display system of a theft preventing apparatus having two kinds of theft prevention

ABSTRACT

The present invention relates to a display system for a theft-preventing apparatus mounted on a vehicle, and an object of the present invention is to provide a display system in which a display device can be commonly used for two kinds of theft-preventing apparatuses. A security ECU (20) outputs a continuous lighting signal when set to a waiting state, and stops outputting the signal in a cautioning state. An immobilizer ECU (22) outputs a blinking signal to a light-emitting device (50) only when the cautioning state is set. Accordingly, the light-emitting device (50) is turned off when both the security apparatus and the immobilizer apparatus are set to a resting state. Additionally, the light-emitting device (50) is continuously lighted when the security apparatus is in the waiting state. Further, the light-emitting device (50) is being blinked when the security apparatus is not set to the waiting state and the immobilizer apparatus is set to the cautioning state.

TECHNICAL FIELD

The present invention relates to a display system of a theft-preventingapparatus provided to a vehicle and, more particularly, to a displaysystem of a theft-preventing apparatus in which a display apparatus canbe commonly used for two kinds of theft-preventing apparatuses.

BACKGROUND ART

Conventionally, a theft-preventing apparatus has been developed forpreventing a theft of a vehicle, parts of a vehicle or an attachment ofa vehicle. The theft-preventing apparatus prevents a theft by generatingan alarm such as a horn or prohibiting a start of the vehicle when thetheft-preventing apparatus detects that an unauthorized person intrudesinto the vehicle.

Japanese Laid-Open Patent Application No.4-197853 discloses such atheft-preventing apparatus. This theft-preventing apparatus enters awaiting mode and starts blinking a display apparatus when doors of avehicle is detected to be locked. In the waiting mode, an alarm is notgenerated even if the doors are unlocked by means other than a key.Thereby, an alarm is prevented from being generated when a passengerremains in the vehicle unlocks a door from inside the vehicle so as toget off from the vehicle after the door was locked. The waiting state iscontinued for a predetermined time period. After the predetermined timeperiod is elapsed, the theft-preventing apparatus shifts from thewaiting state to a cautioning state. In the cautioning state, an alarmsignal is generated by providing a drive signal to a horn or a lamp whenit is detected that one of the doors is opened by means other than thekey or a posture of the vehicle is changed. Additionally, caution isgiven to a person who attempts a theft so as to provided an effect toprevent a theft by continuously blinking the display apparatus in thecautioning state. In the above-mentioned conventional theft-preventingapparatus, a blinking period of the display apparatus is changed betweenthe waiting state and the cautioning state, and, thereby, it is possibleto distinguish the cautioning state from the waiting state.

As a vehicle theft-preventing apparatus different from theabove-mentioned conventional theft-preventing apparatus, for example, anapparatus (referred to as an immobilizer apparatus) for preventing astart of an engine by a key other than a correct key is known. Theimmobilizer apparatus previously provides a key code and a registeredcode to a key and a vehicle, respectively. A start of the engine ispermitted only when the key code matches the registered code. Thus,according to the immobilizer apparatus, it is difficult to start avehicle without using the correct key, and, thereby, the vehicle isprevented from being theft.

The immobilizer apparatus is set to the cautioning state in which astart of the engine is prohibited at the time when the key is removedfrom an ignition-key cylinder. When the immobilizer apparatus is in thecautioning state, the owner of the vehicle is notified that theapparatus is normally operated. At the same time, a display such asblinking of the display apparatus is performed so as to give a cautionto a thief.

As mentioned above, the immobilizer apparatus has the same purpose asthe above-mentioned conventional theft-preventing apparatus with respectto prevention of theft of a vehicle. Accordingly, when both theabove-mentioned conventional theft-preventing apparatus and theimmobilizer apparatus are provided to the same apparatus, time periodsof the waiting states of these apparatuses are substantially equal toeach other. Accordingly, there may be no problem if displays indicatingoperational states of these theft-preventing apparatuses are common toeach other.

However, since the above-mentioned conventional theft-preventingapparatus does not consider common use with the immobilizer apparatus,an exclusive display apparatus must be provided other than that of theimmobilizer apparatus. That is, the above-mentioned theft-preventingapparatus has a problem in that a number of parts is increased since adisplay apparatus must be provided for each theft-preventing apparatuswhen the theft-preventing apparatus is provided together with othertheft-preventing apparatuses.

DISCLOSURE OF THE INVENTION

It is a general object of the present invention to provide an improvedand useful display system for a theft-preventing apparatus in which theabove-mentioned problems are eliminated.

A more specific object of the present invention is to provide a displaysystem for a theft-preventing apparatus in which, when a plurality oftheft-preventing apparatuses are provided, an increase in the number ofparts can be prevented by commonly using a display apparatus so thatchecking of an operation and a state of operation can be positivelyperformed for each of the apparatuses.

In order to achieve the above-mentioned objects, there is providedaccording to one aspect of the present invention a display system for atheft-preventing apparatus for displaying operational states of a firsttheft-preventing apparatus and a second theft-preventing apparatus, thefirst theft-preventing apparatus being set to one of a resting state inwhich a caution with respect to a theft is not performed, a waitingstate in which a start of a caution to a theft is waited for and acautioning state in which a caution to a theft is performed, the secondtheft-preventing apparatus being set to one of the resting state and thecautioning state,

characterized by:

a first signal outputting unit outputting a first signal when the firsttheft-preventing apparatus is in the waiting state;

a second signal outputting unit outputting a second signal when thesecond theft-preventing apparatus is in the cautioning state; and

a display device connected to the first signal outputting unit and thesecond signal outputting unit, the display device provides a displaycorresponding to the first signal when the first signal is output, thedisplay device provides a display corresponding to the second signalwhen the first signal is not output and the second signal is output.

In the above-mentioned invention, the first signal outputting unit ofthe first theft-preventing apparatus outputs the first signal to thedisplay device when the waiting state is set. On the other hand, thesecond signal outputting unit of the second theft-preventing apparatusoutputs the second signal to the display device when the waiting stateis set. The display device provides a display in response to the firstpredetermined signal when the first predetermined signal is output, andprovides a display in response to the second predetermined signal whenthe first predetermined signal is not output and the secondpredetermined signal is output. Thereby, the display device provides adisplay in response to the first signal when the first theft-preventingapparatus is set to the waiting state, and the display device provides adisplay in response to the second signal when the first theft-preventingapparatus is not set to the waiting state and the second-preventingapparatus is set to the cautioning state. Accordingly, one candistinguish, by the display of the display device, a state in which thefirst theft-preventing apparatus is set to the waiting state and a statein which the first theft-preventing apparatus is not set to the waitingstate and at least one of the first and second theft-preventingapparatuses is set to the cautioning state.

In one embodiment of the present invention, the first signal outputtingunit may stop outputting the first signal when one of the cautioningstate and the resting state is set, and the second signal outputtingunit may stop outputting the second signal when the resting state isset.

Additionally, the first signal outputting unit may be provided to thefirst theft-preventing apparatus, and the second signal outputting unitmay be provided to the second theft-preventing apparatus.

Additionally, the display device may include a light-emitting elementhaving a terminal connected to the first signal outputting unit and thesecond signal outputting unit and having an opposite terminal beinggrounded.

Further, the first signal outputting unit may include a first rectifyingelement which permits a flow of the first signal toward the displaydevice and interrupts a flow of the second signal from the second signaloutputting unit, and the second signal outputting unit may include asecond rectifying element which permits a flow of the second signaltoward the display device and interrupts a flow of the first signal fromthe first signal outputting unit.

Additionally, there is provided according to another aspect of thepresent invention a display system for a theft-preventing apparatus fordisplaying an operational state of a first theft-preventing apparatus,the first theft-preventing apparatus being set to one of a resting statein which a caution with respect to a theft is not performed, a waitingstate in which a start of a caution to a theft is waited for and acautioning state in which a caution to a theft is performed, a secondtheft-preventing apparatus being set to one of the resting state and thecautioning state being further provided to the display system, thesecond theft-preventing apparatus having a second signal outputting unitoutputting the second signal when the cautioning state is set,

characterized by:

a first signal outputting unit outputting a first signal representing astate of the first theft-preventing apparatus;

a display device, connected to the first signal outputting unit, forproviding a display in accordance with the first signal, the firstoutputting unit also connectable to the second theft-preventingapparatus;

a determining unit detecting a presence of the second signal from thesecond theft-preventing apparatus; and

a display selecting unit outputting the first signal in accordance witha state of the first theft-preventing apparatus when the determiningunit detects that the second signal is not output from the secondtheft-preventing apparatus, the display selecting unit outputting thefirst signal in accordance with both a state of the firsttheft-preventing apparatus and a state of the second theft-preventingapparatus when the determining unit detects that the second signal ispresent.

In the above-mentioned invention, presence of an output signal (thesecond signal) of the second theft-preventing apparatus is detected bythe determining unit, the second theft-preventing apparatus being set toone of the resting state in which a caution to a theft is not performedand the cautioning state in which a caution to a theft is performed.When it is detected that the output signal of the secondtheft-preventing apparatus is not present, the display selecting unitoutputs the display signal (the first signal) based on the state of thefirst theft-preventing apparatus to the display device. Accordingly, thedisplay device is set to a lighting state corresponding to the state ofthe first theft-preventing apparatus. On the other hand, if it isdetected that the output signal of the second theft-preventing apparatusis present, the output selecting unit outputs to the display device thedisplay signal based on both states of the first theft-preventingapparatus and the second theft-preventing apparatus. Accordingly, thedisplay device is set to a lighting state corresponding to the states ofthe first theft-preventing apparatus and the second theft-preventingapparatus. Thus, the state of each of the theft-preventing apparatusesis displayed on the display device irrespective of presence of theoutput signal of the second theft-preventing apparatus.

Additionally, the second signal outputting unit may stop outputting thesecond signal when the resting state is set.

Additionally, the first signal outputting unit may be provided to thefirst theft-preventing apparatus.

Additionally, the display device may include a light-emitting elementhaving a terminal connected to the first signal outputting unit andhaving an opposite terminal being grounded.

Additionally, the first signal outputting unit may include a firstrectifying element which permits a flow of the first signal toward thedisplay device and interrupts a flow of the second signal from thesecond signal outputting unit, and the second signal outputting unit mayinclude a second rectifying element which permits a flow of the secondsignal toward the display device and interrupts a flow of the firstsignal from the first signal outputting unit.

Further, the determining unit may includes:

a third rectifying element which permits a flow of the second signalfrom the second signal outputting unit and interrupts a reverse flow ofthe second signal; and

a transistor, connected to the third rectifying element, for outputtingone of a high-level signal and a low-level signal in accordance with thesecond signal.

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a display system according to a firstembodiment of the present invention;

FIG. 2 is a time chart of a signal output to a light-emitting devicefrom an immobilizer apparatus ECU and a security ECU and a state oflighting of the light-emitting device in the display system shown inFIG. 1;

FIG. 3 is a circuit diagram of a display system according to a secondembodiment of the present invention;

FIG. 4 is a time chart of a signal output to a light-emitting devicefrom an immobilizer ECU and a security ECU and a state of lighting ofthe light-emitting device in the display system shown in FIG. 1 when animmobilizer apparatus is provided; and

FIG. 5 is a time chart of a signal output to a light-emitting devicefrom a security ECU in the display system shown in FIG. 3 when animmobilizer apparatus is not provided.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a circuit diagram of a display system according to a firstembodiment of the present invention. In the present embodiment, anexample is indicated in which a display apparatus for a theft-preventingapparatus is applied to both a security apparatus which is one kind oftheft-preventing apparatuses and an immobilizer apparatus.

The security apparatus generates an alarm signal to announce anabnormality by driving a horn or a lamp of a vehicle when an abnormalitysuch as opening of a door of the vehicle without using a correct key isdetected. The security apparatus enters a cautioning state via a waitingstate lasting a predetermined time period when all doors of the vehicleare locked. In the cautioning state, an alarm signal is generated whenthe above-mentioned abnormality is detected. In the waiting state, thealarm signal is not generated even when the above-mentioned abnormalityis detected. The waiting state is provided for preventing a generationof the alarm signal which is caused by unlocking the door from inside bya passenger remaining in the vehicle when the door is locked in a statein which the passenger remains in a seat next to the driver or a rearseat.

The immobilizer apparatus receives a code transmitted from a keyinserted into an ignition-key cylinder. A start of the vehicle ispermitted when the code matches a previously stored registered code. Thesecurity apparatus and the immobilizer apparatus are controlled by asecurity electronic control unit (hereinafter referred to as a securityECU) 20 and an immobilizer electronic control unit (hereinafter referredto as an immobilizer ECU) 22, respectively. The security ECU 20 has aCPU 24. A key switch for detecting a locked or unlocked state of a door,a courtesy switch for detecting an open or closed state of each door, ahorn drive relay for driving a horn and a lamp drive relay for driving ahead lamp (each not shown in the figure) are connected to the CUP 24.The CPU 24 control a drive signal provided to each of theabove-mentioned according to outputs of the key switch and the courtesyswitch.

Further, drive transistors 26 and 28 and a light-emitting device drivecircuit 32 comprising a drive diode 30 are connected to an outputterminal 24a of the CPU 24. In the light-emitting device drive circuit32, when the CPU 24 outputs a high-level output to the output terminal24a, the drive transistors 26 and 28 are turned on and a voltagesupplied by a power source 34 is output to a display output terminal 36of the security ECU 20 via the drive diode 30. On the other hand, in astate in which the CPU 24 outputs a low-level output to the outputterminal 24a, the drive transistors 26 and 28 are turned off and avoltage is not output to the display output terminal 36.

The CPU 24 of the security ECU 20 enters the waiting state when itdetects that the door is locked according to an output of the keyswitch. In the waiting state, The CPU 24 outputs a waiting signalindicating the waiting state to the output terminal 24a. As describedlater, the waiting signal is a continuous signal maintaining an ONstate. Further, the CPU 24 enters the cautioning state and stopsoutputting the waiting signal when a predetermined time T is elapsedafter entering the waiting stated. In the cautioning state, the CPU 24outputs drive signals to the horn drive relay and the lamp drive relayso as to generate an alarm when the CPU 24 detects that one of the doorsis opened by means other than a key in accordance with outputs of thekey switch and the courtesy switch.

On the other hand, the immobilizer ECU 22 has a CPU 38. An ignitionswitch for detecting whether or not the key is inserted into theignition key cylinder, a receiving device for receiving a codetransmitted by the key and an engine control unit for controlling anengine (each not shown in the figure) are connected to the CPU 38. TheCPU 38 outputs an engine start permission signal to the engine controlunit when the code output from the receiver matches a previously storedpredetermined registered code. Additionally, a power source 40, drivetransistors 42 and 43 and a light-emitting device drive circuit 46including a drive diode 44 are connected to an output terminal 38a ofthe CPU 38. Similar to the light-emitting device drive circuit 32, thelight-emitting device drive circuit 46 apparatus controls an on and offof an output of a voltage to the output terminal 48 in response to theoutput of the output terminal 38a of the CPU 38.

When the CPU 38 detects that the key is removed from the ignition-keycylinder in accordance with the output of the ignition switch, theimmobilizer apparatus enters the cautioning state. In the cautioningstate, the immobilizer ECU 22 outputs an engine start prohibiting signalto the engine control unit and outputs a caution signal indicating thecautioning signal to the output terminal 48. As described later, thecautioning signal is a pulse-like signal in which an on and off of avoltage is periodically repeated.

The display terminals 36 and 48 of the security ECU 20 and theimmobilizer ECU 20 are connected to an input terminal of alight-emitting device 50. The light-emitting device 50 comprises, forexample, a light-emitting diode that lights when a predetermined voltageis provided thereto.

According to the above-mentioned structure, at least one of the securityECU 20 and the immobilizer ECU 22 outputs a predetermined voltage to thedisplay terminal 36 or 48, the predetermined voltage if provided to thelight-emitting device 50 and, thus, the light-emitting device 50 lights.

It should be noted that, in the above-mentioned structure, when both thesecurity ECU 20 and the immobilizer ECU 22 output the voltage at thesame time, one of the output terminals 36 and 48 are provided with thevoltage output form the other output terminals. The security ECU 20 andthe immobilizer ECU 22 are provided with protective diodes 30 and 44,respectively, the drive transistors 28 and 43 are prevented from beingaffected by the voltage provided to the output terminals 36 and 48.Thereby, the circuits 32 and 46 are prevented from being damaged.

A description will now be given, with reference to FIG. 2, of displaysignals that are output to the display output terminals 36 and 48 fromthe immobilizer ECU 22 and the security ECU 20. FIG. 2 is a time chartof the signals that are output to the display output terminals 36 and 48from the immobilizer ECU 22 and the security ECU 20 and a state oflighting of the light-emitting device 50. In FIG. 2, before a time t1 isa state in which the correct key is inserted into the ignition-keycylinder, and both the immobilizer apparatus and the security apparatusare in a resting state. If the CPU 38 detects, at the time t1, that thekey is removed from the ignition-key cylinder, the immobilizer ECU 22starts to output a periodic blinking signal as shown in FIG. 2-(a).Thereby, the light-emitting apparatus 50 starts to blink as shown inFIG. 2-(c), and the driver is able to recognize that the immobilizerapparatus is normally set in the cautioning state. Thereafter, theimmobilizer ECU 22 continuously outputs the blinking signal until thecorrect key is inserted into the ignition-key cylinder again. Next, ifthe CPU 24 detects, at a time t2, that a door is locked, the securityECU 20 switches the output to the display output terminal 36 to acontinuous lighting signal as shown in FIG. 2-(b).

As mentioned above, the light-emitting device 50 lights when at leastone of the security ECU 20 and the immobilizer ECU 22 outputs apredetermined voltage to the display terminal 36 ort 48. Accordingly,when the security ECU 20 outputs the continuous lighting signal asmentioned above while the immobilizer ECU 22 outputs the blinkingsignal, the light-emitting device 50 is rendered to be in a state inwhich the light-emitting device 50 continuously lights. Thereby, thedriver is able to recognize that the security apparatus is normally setin the waiting state. Additionally, when a passenger remains inside thevehicle, the passenger inside the vehicle is able to recognize that thewaiting state is set in which an alarm is not generated if a door isunlocked form inside the vehicle as long as the light-emitting device 50continuously lights.

At a time t3 when a predetermined time T has elapsed after the time t2,the security apparatus is shifted from the waiting state to thecautioning state. At the time t3, the security ECU 20 stops outputtingthe continuous lighting signal, while the immobilizer ECU 22continuously outputs the blinking signal after the time t3. Accordingly,after the time t3, the light-emitting device 50 is set to the blinkingstate again. Thereby, it is notified that the security apparatus isshifted from the waiting state to the cautioning state. Additionally, acaution is given to an unauthorized person by announcing that thetheft-preventing apparatus is in operation by blinking of thelight-emitting device 50, and, thus, there is an effect to prevent atheft from happening.

As mentioned above, in the system of the present embodiment, thelight-emitting device 50 takes one of the unlighting state, thecontinuous lighting state and the blinking state in response tooperational states of the immobilizer apparatus and the securityapparatus, and, thereby, the operational states of two theft-preventingapparatus can be correctly displayed by the single light-emitting device50.

Each of the above-mentioned immobilizer apparatus and the securityapparatus can be independently mounted on a vehicle. Thus, according toa specification of optional parts, only one of the theft-preventingapparatus may be provided. In the system according to the presentinvention, even when only the immobilizer apparatus is mounted and thesecurity apparatus is not mounted, an operational state of theimmobilizer apparatus is displayed on the light-emitting device 50, asmentioned above, by the immobilizer ECU 22 outputting the blinkingsignal when the key is removed from the ignition-key cylinder. Thus,according to the system of the present embodiment, an operational stateof the immobilizer apparatus can be correctly displayed without changingthe structure of the immobilizer ECU 22 and the light-emitting device 50and a routine for displaying performed by the CPU 38 of the immobilizerECU 22 irrespective of presence of the security apparatus. Accordingly,the system of the present embodiment has a flexibility to be adapted tovarious optional specifications of the theft-preventing apparatuses.

It should be noted that, in the above-mentioned first embodiment, thesecurity apparatus corresponds to a first theft-preventing apparatus,the immobilizer apparatus corresponds to a second theft-preventingapparatus and the light-emitting device 50 corresponds to a displayapparatus.

FIG. 3 shows a circuit diagram of a display system according to a secondembodiment of the present invention. In the present embodiment, similarto the above-mentioned first embodiment, an example is indicated inwhich the display system for the theft-preventing apparatus according tothe present invention is applied to the security apparatus and theimmobilizer apparatus. It should be noted that, in FIG. 3, parts thatare the same as the parts shown in FIG. 1 are given the same referencenumerals, and descriptions thereof will be omitted.

As shown in FIG. 3, an immobilizer apparatus presence determiningcircuit 62 is connected between the display output terminal 36 of thesecurity ECU 20 and the input terminal 24b of the CPU 24. Theimmobilizer apparatus presence determining circuit 62 comprises atransistor 64, a diode 66 and a resistor 68. A collector of thetransistor 64 is connected to the input terminal 24b of the CPU 24 andthe power source 34, and an emitter thereof is grounded. The resistor 68and the diode 66 are connected in series between the output terminal 36of the security ECU 20 and a base of the transistor 64. The diode 66 isprovided so that a direction from the output terminal 36 to thetransistor 64 corresponds to a normal direction. It should be notedthat, in the system of the present embodiment, an ignition switch isalso connected to the CPU 24 so as to detect whether or not a key isinserted into the ignition-key cylinder.

According to the above-mentioned structure, when the immobilizer ECU 22outputs a voltage to the display output terminal 48, the voltage isprovided to the base of the transistor 64 via the display outputterminal 36, the resistor 68 and the diode 66. In this state, since thetransistor 64 is turned on, a low-level input is input to the terminal24b of the CPU 24. On the other hand, in a state in which the securityECU 20 does not output a voltage to the output terminal 36 and theimmobilizer apparatus outputs a voltage to the output terminal 48, thevoltage is not provided to the base of the transistor 64. In this state,since the transistor 64 is turned off, a high-level input is input tothe input terminal 24b of the CPU 24.

In the system according to the present invention, similar to the systemof the above-mentioned first embodiment, when the immobilizer ECU 22detects that the key is removed from the key cylinder, the immobilizerECU 22 starts to output the blinking signal as shown in FIG. 4(b).Accordingly, the CPU 24 of the security ECU 20 can detect whether or notthe immobilizer apparatus is mounted by checking a state of the inputterminal 24b after detecting that the key is removed from the keycylinder based on the output of the ignition switch.

As mentioned above, the security ECU 20 performs a determination as towhether or not the immobilizer apparatus is mounted by inputting thedisplay signal output by the immobilizer ECU 22 to the input terminal24b of the CPU 24 via the immobilizer apparatus presence determinationcircuit 62. In this case, if a noise enters the input terminal 24b,there is a possibility that an erroneous recognition is made that theimmobilizer apparatus is present although the immobilizer apparatus isnot mounted. In order to prevent such an erroneous recognition, the CPU24 performs a filtering of the input signal to the input terminal 24b bya low-pass filter and performs the determination as to whether or notthe immobilizer apparatus is mounted based on the filtered signal.Accordingly, a slight time delay is generated after the immobilizer ECU22 starts the output of the display signal and until the security ECU 20detects the display signal. Additionally, a slight time delay isgenerated due to a process time of the CPU 38 after the key is removedfrom the ignition-key cylinder and until the immobilizer ECU 22 startsto output the display signal. As mentioned above, in the system of theabove-mentioned embodiment, a slight time delay is generated after thekey is removed from the ignition-key cylinder and until the security ECU20 correctly detects presence of the immobilizer apparatus.

Accordingly, if the security ECU 20 determines presence of theimmobilizer apparatus immediately after the doors are locked, it ispossible that the immobilizer apparatus is mounted is not correctlydetected although the immobilizer apparatus is actually mounted due tothe above-mentioned time delay when the driver locks the doors beforethe above-mentioned time delay has not been elapsed after the driverremoves the key.

In order to eliminate such an inconvenience, in the system according tothe above-mentioned embodiment, the CPU 24 of the security ECU 20detects as to whether or not the immobilizer is mounted when apredetermined waiting time has been elapsed after it is detected thatthe key is removed from the ignition-key cylinder. Thereby, the CPU 24is prevented from erroneously detecting presence of the immobilizerapparatus.

The security ECU 22 outputs two kinds of display signals in accordancewith presence of the immobilizer apparatus detected as mentioned above.FIG. 4 shows a time chart of the display signal output by the securityECU 20 when the immobilizer is mounted, together with a time chart ofthe display signal output by the immobilizer ECU 22 and a lighting stateof the light-emitting device 50. As shown in FIG. 4-(a), when theimmobilizer ECU 22 detects that the key is removed from the ignition-keycylinder at a time t4, the immobilizer ECU 22 starts to output theblinking signal to the display output terminal 48. The security ECU 20detects that the immobilizer apparatus is mounted by detecting a firstpule wave of the blinking signal.

If it is detected, at a time t5, that the doors are locked, the securityECU 20 starts to output the continuous lighting signal which indicatesthe waiting state, and stops outputting the continuous lighting signalat a time t6 when a predetermined time period has been elapsed after thetime t5.

Similar to the above-mentioned first embodiment, the light-emittingdevice 50 lights when a voltage is output to at least one of the outputterminal 48 of the immobilizer apparatus and the display output terminal36 of the security ECU 20. Accordingly, similar to the above-mentionedfirst embodiment, the light-emitting device 50 starts blinking at thetime t4 and continuously lights at the time t5, and, thereafter, thelight-emitting device 50 blinks again at the time t6. As mentionedabove, when the security apparatus and the immobilizer apparatus aremounted, operational states of these apparatuses can be correctlydisplayed by the light-emitting device 50 taking one of the three statessuch as the unlighting state, the blinking state and the continuouslighting state in response to operational states of the securityapparatus and the immobilizer apparatus.

FIG. 5 shows a time chart of the display signal output by the securityECU 20 when it is detected that the immobilizer apparatus is notmounted. The CPU 24 of the security ECU 24 detects that the immobilizerapparatus is not mounted by the fact that the high-level input is notinput to the input terminal 24b after detecting the key being removedfrom the ignition-key cylinder based on the output of the ignitionswitch. In this case, if it is detected that the doors are locked at atime t8, the security ECU 20 is set to the waiting state and starts tooutput the continuous lighting signal. Then, at a time t9 when thepredetermined waiting time T has been elapsed after the time t8, theoutput to the light-emitting device 50 is switched from the continuouslighting signal to the blinking signal which indicates the cautioningstate. Thereafter, the blinking signal is continuously output until thedoors are unlocked by a method using a correct key.

As mentioned above, in the system according to the present invention,when the immobilizer is not mounted, the non-operating state, thewaiting state and the cautioning state of the security apparatus can bedisplayed by the light-emitting device 50 by the security ECU 20outputting the display signal as shown in FIG. 5.

It should be noted that when the immobilizer apparatus is mounted butthe immobilizer apparatus is malfunctioning, the signal output by theimmobilizer ECU 22 is not detected by the presence determining circuit62. Accordingly, in such a case, similar to a case in which theimmobilizer is not mounted, the security ECU 20 output the displaysignal as shown in FIG. 5. That is, even when the mounted immobilizerapparatus is malfunctioning, the non-operating state, the waiting stateand the cautioning state of the security apparatus can be displayed bythe light-emitting device 50.

As mentioned above, in the system according to the present embodiment,the security ECU 20 is provided with the immobilizer apparatus presencedetermining circuit 62 and the CPU 24 performs a routine to selectivelyoutput one of the display signal shown in FIG. 4-(a) and the displaysignal shown in FIG. 5 according to the signal from the immobilizerapparatus presence determining circuit 62. Thereby, the operationalstates of the security apparatus and the immobilizer apparatus can beappropriately displayed on the light-emitting device 50 when theimmobilizer apparatus is mounted, and the operational state of thesecurity apparatus can be appropriately displayed on the light-emittingdevice 50 when the immobilizer apparatus is not mounted.

Additionally, in the above-mentioned embodiment, when the securityapparatus is not mounted and only the immobilizer apparatus is mounted,the light-emitting device 50 blinks in response to the display signaloutput by the immobilizer ECU 22. Accordingly, an operational state ofthe immobilizer apparatus can be correctly displayed on thelight-emitting device 50 by the immobilizer ECU 22 starting to outputthe blinking signal at a time when a removal of the key is detected.Thus, according to the system of the present embodiment, the operationalstates of the security apparatus and the immobilizer apparatus can beappropriately displayed on the light-emitting device 50 without changingthe structure of the immobilizer ECU 22 and a routine for displayperformed by the CPU 38 when the immobilizer apparatus is mounted, andthe operational state of the immobilizer apparatus can be appropriatelydisplayed on the light-emitting device 50 without changing the structureof the immobilizer ECU 22 and a routine for display performed by the CPU38 when only the immobilizer apparatus is mounted.

Thus, according to the system of the present embodiment, both in thecase in which the security apparatus and the immobilizer apparatus aremounted and the case in which only one of them is mounted, anoperational state of the mounted theft-preventing apparatus can bedisplayed on the light-emitting device 50 without changing the structureof the ECU of each of the security apparatus and the immobilizerapparatus and contents of a routine performed by the CPU of each of thesecurity apparatus and the immobilizer apparatus.

As mentioned above, according to the present embodiment, a displaysystem for a theft-preventing apparatus can be achieved in which anumber of light emitting devices is prevented from being increased whentwo kinds of theft-preventing apparatuses are provided, and a flexiblecan be obtained with respect to arbitrary mounting specifications of thesecurity apparatus and the immobilizer apparatus.

Additionally, according to the system of the present invention, whenboth the security apparatus and the immobilizer apparatus are mountedand if one of them is cannot output the display signal due tomalfunctioning, the other of them can provide the display signal to thelight-emitting device 50. Accordingly, in such a case, thelight-emitting device 50 can be blinked when one of the theft-preventingapparatus is in the cautioning operation, and, thereby, an effect forcautioning to a person attempting a theft can be maintained.

It should be noted that, in the above-mentioned second embodiment, thesecurity apparatus corresponds to a first theft-preventing apparatus,the immobilizer apparatus corresponds to a second theft preventingapparatus, the light-emitting device 50 corresponds to a displayapparatus and the immobilizer apparatus presence determining circuit 62corresponds to a determining unit. Additionally, a display selectingunit is achieved by the security ECU selectively outputting the signalshown in FIG. 4-(a) or the signal shown in FIG. 5 in accordance withpresence of the immobilizer.

As mentioned above, according to the present invention, an operation andan operational state of each of the first theft-preventing apparatus andthe second theft-preventing apparatus can be displayed by a commondisplay device so that the recognition of the operation and theoperational states can be positively performed. Thereby, when the firsttheft-preventing apparatus and the second theft-preventing apparatus areprovided, a number of the display devices is prevented from beingincreased.

Additionally, according to the present invention, an operation and anoperational state of each of the first theft-preventing apparatus andthe second theft-preventing apparatus can be displayed on a commondisplay device, and, thereby, a number of the display devices isprevented from being increased when the first theft-preventing apparatusand the second theft-preventing apparatus are provided. Further, achange in the structure of the first theft-preventing apparatus isunnecessary irrespective of presence of the second theft-preventingapparatus. Thereby, a flexibility of the first theft-preventingapparatus with respect to various mounting specifications of thetheft-preventing apparatuses is improved.

The present invention is not limited to the specifically disclosedembodiments, and variations and modifications may be made withoutdeparting from the scope of the present invention.

What is claimed is:
 1. A display system for a theft-preventing apparatusfor displaying operational states of a first theft-preventing apparatusand a second theft preventing apparatus, said first theft-preventingapparatus being set to one of a resting state in which a caution withrespect to a theft is not performed, a waiting state in which a start ofa caution to a theft is waited for and a cautioning state in which acaution to a theft is performed, said second theft-preventing apparatusbeing set to one of the resting state and the cautioningstate,characterized by: a first signal outputting unit (20) outputting afirst signal when said first theft-preventing apparatus is in saidwaiting state; a second signal outputting unit (22) outputting a secondsignal when said second theft-preventing apparatus is in said cautioningstate; and a display device (50) connected to said first signaloutputting unit (20) and said second signal outputting unit (22), saiddisplay device provides a display corresponding to said first signalwhen said first signal is output, said display device provides a displaycorresponding to said second signal when said first signal is not outputand said second signal is output.
 2. The display system for atheft-preventing apparatus as claimed in claim 1, characterized in thatsaid first signal outputting unit (20) stops outputting said firstsignal when one of said cautioning state and said resting state is set,and said second signal outputting unit (22) stops outputting said secondsignal when said resting state is set.
 3. The display system for atheft-preventing apparatus as claimed in claim 1, characterized in thatsaid first signal outputting unit (20) is provided to said firsttheft-preventing apparatus, and said second signal outputting unit (22)is provided to said second theft-preventing apparatus.
 4. The displaysystem for a theft-preventing apparatus as claimed in claim 1,characterized in that said display device (50) includes a light-emittingelement (50) having a terminal connected to said first signal outputtingunit (20) and said second signal outputting unit (22) and having anopposite terminal being grounded.
 5. The display system for atheft-preventing apparatus as claimed in claim 1, characterized in thatsaid first signal outputting unit (20) includes a first rectifyingelement (30) which permits a flow of the first signal toward saiddisplay device (50) and interrupts a flow of said second signal fromsaid second signal outputting unit (22), and said second signaloutputting unit (22) includes a second rectifying element (44) whichpermits a flow of the second signal toward said display device (50) andinterrupts a flow of said first signal from said first signal outputtingunit (20).
 6. A display system for a theft-preventing apparatus fordisplaying an operational state of a first theft-preventing apparatus,said first theft-preventing apparatus being set to one of a restingstate in which a caution with respect to a theft is not performed, awaiting state in which a start of a caution to a theft is waited for anda cautioning state in which a caution to a theft is performed, a secondtheft-preventing apparatus being set to one of the resting state and thecautioning state being further provided to said display system, saidsecond theft-preventing apparatus having a second signal outputting unit(22) outputting the second signal when said cautioning state isset,characterized by: a first signal outputting unit (20) outputting afirst signal representing a state of said first theft-preventingapparatus; a display device (50), connected to said first signaloutputting unit (20), for providing a display in accordance with saidfirst signal, said first outputting unit (20) also connectable to saidsecond theft-preventing apparatus; a determining unit (62) detecting apresence of said second signal from said second theft-preventingapparatus; and a display selecting unit (24) outputting said firstsignal in accordance with a state of said first theft-preventingapparatus when said determining unit (62) detects that said secondsignal is not output from said second theft-preventing apparatus, saiddisplay selecting unit (24) outputting said first signal in accordancewith both a state of said first theft-preventing apparatus and a stateof said second theft-preventing apparatus when said determining unit(62) detects that said second signal is present.
 7. The display systemfor a theft-preventing apparatus as claimed in claim 6, characterized inthat said second signal outputting unit (22) stops outputting saidsecond signal when said resting state is set.
 8. The display system fora theft-preventing apparatus as claimed in claim 6, characterized inthat said first signal outputting unit (20) is provided to said firsttheft-preventing apparatus.
 9. The display system for a theft-preventingapparatus as claimed in claim 6, characterized in that said displaydevice (50) includes a light-emitting element (50) having a terminalconnected to said first signal outputting unit (20) and having anopposite terminal being grounded.
 10. The display system for atheft-preventing apparatus as claimed in claim 6, characterized in thatsaid first signal outputting unit (20) includes a first rectifyingelement (30) which permits a flow of the first signal toward saiddisplay device (50) and interrupts a flow of said second signal fromsaid second signal outputting unit (22), and said second signaloutputting unit (22) includes a second rectifying element (44) whichpermits a flow of the second signal toward said display device (50) andinterrupts a flow of said first signal from said first signal outputtingunit (20).
 11. The display system for a theft-preventing apparatus asclaimed in claim 6, characterized in that said determining unit (62)includes:a third rectifying element (66) which permits a flow of thesecond signal from said second signal outputting unit and interrupts areverse flow of said second signal; and a transistor (64), connected tosaid third rectifying element (66), for outputting one of a high-levelsignal and a low-level signal in accordance with said second signal.